The incidence of colon cancer has increased Worldwide. In the U.S. it is down but still at high levels. The word "significant" you quoted refers to the statiscal reliability of the recent studies not the amount of the decrease. The decrease is probably the result of less smoking and use of bad fats in the diet. I was unable to paste in the graph for the U.S., but you can find it in many places through a search. Here are the conclusions of the most recent scientific study:
"Results: Colorectal cancer incidence rates for both males and females "statistically significantly" increased from 1983-87 to 1998-2002 for 27 of 51 cancer registries considered in the analysis, largely confined to economically transitioning countries including Eastern European countries, most parts of Asia, and select countries of South America. These increases were more prominent for men than for women. We also observed substantial variations in colorectal cancer incidence trends within countries such as Japan. Similarly, trends in Israel and Singapore varied significantly according to ethnicity. The United States is the only country where colorectal cancer incidence rates declined in both males and females."